The hypothesis which this proposal aims to test is whether laminin and fibronectin, extracellular matrix glycoproteins of peripheral and/or central nervous system (9, 22, 26), can guide the direction of neurite elongation of peripheral and central neurons. Laminin and fibronectin have been shown to stimulate neurite elongation in both central and peripheral neurons. The extent of these effects is different for peripheral and central neurons (4, 13, 24, 27, 28, 31). It is not conclusively known whether laminin and fibronectin can guide the direction of axon elongation for either central or peripheral neurons, or increase neurite-substratum adhesion. The proposed research would provide a "spectrum of action" for laminin and fibronectin in terms of neurite guidance and neurite-substratum adhesion for central and peripheral neurons. In order to test the hypothesis of directed neurite growth via laminin and fibronectin, spinal cord, dorsal root, and retinal neurons will be obtained from chick embryos and maintained in vitro on special substrates. The recently developed technique of creating highly patterned substrates, which present an elongating neurite with repeating choices between two or three different substrates, will be used to assess whether elongating neurites are guided by exhibiting a substrate preference (16, 17, 18). Adhesion measurement techniques (15, 16, 17) will be used to examine possible increases in neurite-substratum adhesion. The results of these experiments will help determine if laminin and/or fibronectin can guide the direction of neurite growth possibly by an adhesion related mechanism. These experiments will serve as a basis for longer term objectives of continuing to study directional control of neurite growth and eventually applying the results to in vivo systems. The proposed studies are not immediately health related, but may hopefully serve as a basis for aiding regeneration in adult spinal cord and peripheral nerves.